title: First-principles density functional theory (DFT) study of gold nanorod and its interaction with alkanethiol ligands.
abstract: The structure and mechanical properties of gold nanorods and their interactions with alkenthiolate self-assembled monolayers have been determined using a novel first-principle density functional theory simulation approach. The multifaceted, 1-dimensional, octagonal nanorod has alternate Au100 and Au110 surfaces. The structural optimization of the gold nanorods was performed with a mixed basis: the outermost layer of gold atoms used double-ζ plus polarization (DZP), the layer below used double-ζ (DZ), and the inner layers used single-ζ (SZ). The final structure compares favorably with simulations using DZP for all atoms. Phonon dispersion calculations and ab initio molecular dynamics (AIMD) were used to establish the dynamic and thermal stability of the system. From the AIMD simulations it was found that the nanorod system will undergo significant surface reconstruction at 300 K. In addition, when subjected to mechanical stress in the axial direction, the nanorod responds as an orthotropic material, with uniform expansion along the radial direction. The Young's moduli are 207 kbar in the axial direction and 631 kbar in the radial direction. The binding of alkanethiolates, ranging from methanethiol to pentanethiol, caused formation of surface point defects on the Au110 surfaces. On the Au100 surfaces, the defects occurred in the inner layer, creating a small surface island. These defects make positive and negative concavities on the gold nanorod surface, which helps the ligand to achieve a more stable state. The simulation results narrowed significant knowledge gaps on the alkanethiolate adsorption process and on their mutual interactions on gold nanorods. The mechanical characterization offers a new dimension to understand the physical chemistry of these complex nanoparticles.
authors.affiliation: Department of Chemical Engineering, McGill University , 845 Sherbrook Street West, Montreal, Quebec, Canada , H3A 0G4.
authors.forename: Hang
authors.initials: H
authors.lastname: Hu
authors.forename: Linda
authors.initials: L
authors.lastname: Reven
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rey
mesh_terms: D006046:Gold / Q000737:chemistry*; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D008024:Ligands; D013438:Sulfhydryl Compounds; D006046:Gold